Gas hydrate material recovery apparatus

ABSTRACT

A gas hydrate material recovery apparatus utilizing a vessel which is positioned beneath a body of water and above the bed of the body of water. The vessel includes a holding tank with an entrance to capture solid natural gas hydrate crystals. An agitator located below the entrance to the vessel frees methyl hydrate crystals located below the floor of the body of water.

BACKGROUND OF THE INVENTION

The present invention relates to a novel and useful gas hydrate material recovery apparatus.

Gas hydrates are crystalline forms of natural gas such as methane and are maintained in a solid form at extremely low temperatures and pressures of several hundred pounds per square inch or at temperatures below freezing and at atmospheric pressure. Typically, gas hydrate solids, in the crystalline form are found below the floor of bodies of water such as sea beds forming continental shelves. It is estimated that deposits of solid gas hydrates can be hundreds of meters in thickness and represent a concentration of 160 times greater than natural gas, on a volume metric basis.

Although it is known that such gas hydrates in crystalline form exist, exploitation or recovery of gas hydrates has been limited in scope in the past. However, many methods have been proposed to achieve this result.

For example, Japanese Patent Application 07318848 and 09147242 describe the injecting of warm sea water into the methyl hydrate layer and recovering the same through a collecting conduit.

United States Patent Application publication US2005/0107648 and European Patent Application EP1375630 describe a gas hydrate production device in which gas hydrate slurry is fed to a pressure vessel and includes a drain and a cooling device, which forms solid gas hydrate material. The gas hydrate material in powder form is then consolidated into blocks and taken to the atmosphere for use.

United States Patent Application 20050161217 shows a methane hydrate recovery system in which a pair of electrodes are positioned on opposite side of a methane hydrate formation. When voltage is applied to the electrodes, gasses flow from the gas hydrate formation to a gas storage facility.

United States Patent Application 203/0178195 and Wipo publication WO03/021079 describe gas hydrate recovery systems in which the subsurface hydrate formation is located through a conduit, gas is released by the application of heat from an exterior source or from the conversion of the solid hydrate material. The gas is drawn off the deposit to a storage area.

U.S. Pat. Nos. 5,950,732 and 6,299,256 describe systems for recovering gas hydrate in which a collector is positioned over the hydrate formation and includes a conduit which transports the hydrate gas to the surface of the body of water where a ship collects the same.

A system for recovering gas hydrate material in a simple and efficient manner would be a notable advance in the field of energy production.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention a novel and useful gas hydrate material recovery apparatus is herein provided.

The apparatus of the present invention includes, in one aspect of the invention, a vessel having walls which form an inner chamber. The vessel is useable below the surface of a body of water and is intended to lie on the bed or floor of the body of water above a deposit of gas hydrate material. The vessel includes and inlet and an outlet. The inlet is intended to communicate in order to receive natural gas from the source. The outlet serves to conduct natural gas from the vessel when the vessel is moved to the surface of the body of water after being filled with natural gas in hydrate form.

An anchor holds the vessel below the surface of the body of water and is removable from the vessel. In this regard, the vessel may include expandable or flexible portions in order to gather the natural gas hydrate material therewithin over a period of time. It should be noted that the vessel of the present invention is not intended to continuously deliver natural gas hydrate material to storage facility on the surface of the water or on adjacent land masses. Also, a passageway is found in the present invention for permitting the entrance and egress of water relative to the vessel chamber. Such passageway is intended to allow for the changes in volume of the natural gas hydrate material within the vessel when converting phases between a gaseous form and a solid form.

A cooler is also employed for removing heat from the chamber of the vessel. The cooler may take the form a plurality of conduits passing through the chamber of the vessel. Each of the conduits carries cooling fluid to effect a heat exchange between the gas hydrate material and the conduits in order to maintain the gas hydrate in its solid phase, since crystallization of natural gas is an exothermic process. Sea water at or about 0° C. (500 meters below the surface) may be used as a source of coolant.

Also, a vibrator or other similar item may be employed to impart a force on the walls of the vessel in order to allow compacting of the solid form of the natural gas being recovered i.e. the gas hydrate material. Such vibrator may lie on the outer wall of the vessel or be located within the vessel, as the case may be. A level indicator, such as a video with a light source, a sonic probe, etc. would also indicate the position of the gas hydrate material within the chamber to asses the progress of the filling of the vessel in order to determine its status for storage or transportation for the purpose of unloading the gas hydrate material. A recirculation conduit may also be used to transport natural gas between portions of the vessel chamber, in order to augment the formation or solidification process of the natural gas hydrate material. That is to say, the gaseous material which tends to form above the solid layer of the gas hydrate in its solid phase is more easily converted into the solid phase by movement of the same to a position below the solid layer within the vessel.

In another embodiment of the present invention recovery apparatus herein described includes a vessel having an inner chamber formed by walls with and inlet and an outlet. However, the inlet to the chamber forms a mouth which may flare or funnel from the bottom portion of the vessel to receive solid gas hydrate particles. In other words, the feed to the chamber of the vessel includes gas hydrate material which is not in vapor form. The source of the solid gas hydrate particles below the vessel in this embodiment are released by agitation of the solid layer below the floor of the body of water. Such agitation may be effected by mechanical or, hydraulic means. Since the gas hydrate solid particles posses a density of less than that of the water body, the gas hydrate particles float upwardly into the mouth of the vessel for collection. In this regard, a door may be employed to control access to the vessel at the vessel inlet. In this manner, the door remains open when particles are being collected, and closes when the vessel is transported to the surface of the body of water via a ship or to a shore facility for recovery of the natural gas.

Again, an anchor removably holds the vessel below the surface of the water on the floor in order to permit transportation of the vessel as desired. A passageway is also included for egress and entrance of water into the vessel chamber, the former process taking place during the gathering of solid gas hydrate particles within the vessel chamber. Again, a vibrator or other similar mechanism may be used to impart a force on the walls of the vessel, while a level indicator or video monitor is also employed to determine the filling of the vessel chamber.

Further, the freeing of the gas particles from beneath the floor of the body of water may be accomplished by injection of fluid either from the body of water itself, or from a separate source. In essence, the fluid is employed to impart mechanical agitation to the sediment to free the solid gas hydrate particles in order to the particles to rise into the vessel located above the floor of the body of water.

It may be apparent that a novel and useful gas hydrate material recovery apparatus has been herein above described.

It is therefore an object of the present invention to provide a gas hydrate recovery apparatus which is capable of storing gas hydrate material for a period of time and is moveable to a storage facility when a certain level of fill has been attained.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which is capable of receiving natural gas and converting the same into gas hydrate particulate matter or gas hydrate particulate matter directly from beneath the floor of the body of water such as a sea bed.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which is capable of storing natural gas as hydrate on the sea bed or floor of a body of water until surface transport to a destination for use takes place.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which minimizes arrays of conduits and other connections, such as cables, which could serve as a hazard to navigation.

Another object of the present invention is to provide a gas hydrate material recovery apparatus in which natural gas, such as methane, is stored in its concentrated solid hydrate form and results in an economical method of gathering and storing methane for eventual use.

A further object of the present invention is to provide a gas hydrate material recovery apparatus which is useable for harvesting natural gas from below the floor of a body of water in a large number of areas near or far from continental land masses.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which gathers gas hydrates and produces natural gas with minimal sulfur.

Yet another object of the present invention is to provide a gas hydrate material recovery apparatus which will reduce the cost of production of natural gas to industrial, power generation, and transportation facilities.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which reduces reliance on other fossil fuel such as coal or oil.

Another object of the present invention is to provide a gas hydrate material recovery apparatus which recovers natural gas from below the sea bed of oceans on the earth and eliminates the need for refining of fossil fuels found with oil and gas.

The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a side elevational view of the first embodiment of the present invention with vessel chamber shown in broken-away format.

FIG. 2 is a side elevational view of another embodiment of the present invention with a central portion of the apparatus being shown in broken-away format.

FIG. 3 is a schematic view showing vessel of FIG. 1 filled with water.

FIG. 4 is a schematic view of the vessel of FIG. 1 shown filled with water, solid gas hydrate, and gas.

FIG. 5 is a schematic sectional view of the vessel of FIG. 1. depicted as being filled with solid methyl hydrate particles.

For a better understanding of the invention reference is made to the following detailed description of the preferred embodiments of which should be taken in conjunction with the prior described drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Various aspects of the present invention will evolve from the following detailed description of the preferred embodiments thereof which should be taken together with the heretofore delineated drawings.

A preferred embodiment of the present invention is depicted in FIG. 1 by reference character 10A. Apparatus 10A is formed with a vessel 12 having a top 14, and a bottom 16. Side walls 18, contiguous with top 14 and bottom 16, form a chamber 20 within vessel 12. A source of natural gas originating from a natural gas hydrate source (not shown) is directed into chamber 18 via conduit 22. Vessel 12 sits atop floor 24 which may be a sea bed for body of water 26, which may be an oceanic body. Vessel 12 is located above floor 24 by supports 28 and 30, which also serve as anchors for removably holding vessel 12 in the position depicted in FIG. 1. That is to say, anchor supports 28 and 30 are separable from vessel 12 by a suitable latching mechanism. Alternatively, anchor supports 28 and 30 are connected to rods 32 and 34. Rods 32 and 34 are engaged by lifting cables (not shown) through eyes 36 and 38 which are formed at the top portion of rods 32 and 34, respectively, FIG. 1. Consequently, vessel 12 and anchor supports 28 and 30 may be moved upwardly from floor 24 as a unit in this aspect of the invention.

A cooler 39 is also found in the embodiment 10A of the present invention, FIG. 1, in the form of cooling conduits 40, 42, and 44. That is to say, cooling fluid is passed through conduits 40, 42, and 44 in order to remove heat from chamber 18 holding natural gas originating at entrance conduit 22. Of course, cooling conduits 40, 42, and 44 may use body of water 26 as a source of cooling fluid. In addition an outside source of cooling fluid may be fed into cooling conduits 40, 42, and 44. Further, conduits 40, 42, and 44 are detachable and sealable from any other conduits employed to feed cooling fluid into the same when vessel 12 is lifted from floor 24. Vibrators 44 and 46 are intended to impart force on walls 18 of vessel 12 in order to enhance the solidification of the gas hydrate material entering vessel chamber 20 through inlet conduit 22. In this regard, in the depiction of FIG. 1, chamber 20 contains a water layer 50, a layer of solid gas hydrate 52, and a layer of gaseous natural gas 54. A recirculation conduit 56 directs natural gas into the bottom of chamber 20 from the top of chamber 20 directional arrow 58 water check valves 61 and 63 shown in phantom on FIG. 1, permit water displaced from water level 50 to exit chamber 20 of vessel 12 as the solid gas hydrate layer 52 accumulates within chamber 20. Outlet 59 or inlet 22 may serve as an exit for any natural gas accumulating within chamber 20 when vessel 12 is lifted from floor 24.

Turning now to FIG. 2, it may be observed that another embodiment of the apparatus of the present invention 10B is shown. Apparatus 10 includes a vessel 60 which may be in the form of a vertical cylinder. Vessel 60 is formed by wall portion 62 which may be a flexible body. That is to say, walls portion 62 may expand with the filling of chamber 64 formed within vessel 60 by wall portion 62. In this regard, vessel 60 possesses an inlet 66 which is formed by a flared mouth 68 which lies over bed 24 of body of water 26. Mouth 68, as a portion of vessel 60, is found directly above gas hydrate deposit 70 which is located below floor 24 in bed 72. Mouth 66 is supported above and on floor 24 by anchors 74 and 76 which are connected to supports 78 and 80 respectively. It should be noted that other anchors and supports are used with vessel 60 and mouth portion 68 in this regard, but are not shown for the sake of simplicity and clarity. Outriggers 82 and 84 extend along floor 24 to add further support to vessel 60, doors 86 provide access to cylindrical portion 88 of vessel 60, directional arrows 90. Cables 92 and 94 extend from cylindrical portion 88 of vessel 60 and are themselves anchored to floor 24 (not shown) to add further support to vessel 60.

An agitator 96 is also found in apparatus 10B and takes the form of concentric conduits 98 which introduce liquid into deposit 70, directional arrow 100. The outer conduit 102 may form an annular chamber with inner conduit 104 to allow circulation of fluid for the purpose of heating and the like. Pump 106 mounts to the wall 62 of vessel 60 while concentric conduits 98 pass through and are supported by mouth 68. Agitator 96 releases solid gas hydrate material from deposit 100 for capture by mouth 68 and eventual passage into chamber 64 of vessel 60. Vibrator 106 aids in the packing of solid hydrate material within chamber 62 while level monitor 108, in two parts, determines the filling of chamber 64 by gas hydrate particles emanating from deposit 100 due to agitator 96, directional arrow 110. Hooks 112 and 114 permit the lifting of vessel 60 from bed 24 when chamber 64 is filled in order to recover natural gas from the solid gas hydrate particles 112 within chamber 64.

In operation, the user places apparatus 10A on bed 24 to serve as a gathering mechanism for natural gas which enters chamber 18 of vessel 12 via conduit 22. Of course, natural gas entering conduit 22 originates with gas hydrate deposit such as gas hydrate deposit 100 if FIG. 2, directional arrow 114. Gaseous material entering chamber 18 of vessel 12 is formed into a solid gas hydrate layer 52 which eventually occupies the entire chamber 18 thereof. Such solidifications achieved by the use of cooling conduits 40, 42, and 44 and recirculation conduit 56 for the directing of gas layer 54 into water layer 50. Vessel 12 is then lifted from bed 64 when filled for unloading to a ship or a land facility. Eyes 36 and 38 aid in this endeavor. FIGS. 3-5 illustrate the progression of the contents of chamber 18 of vessel 12, schematically. FIG. 3 depicts vessel chamber 18 being filled with water layer 50. FIG. 4 indicates the partial filling of chamber 18 in which water layer 50 lies below a solid gas hydrate layer 52 which is topped by a gas layer 54 comprised of natural gas. Finally, FIG. 5 Indicates a filled vessel 12 in which only solid gas hydrate material 52 lies within chamber 18 since the water has left chamber 20 via optional check valves 61 and 63. Embodiment 10B vessel 60 is similarly filled, except that the solid gas hydrate particles 112 emanate from a deposit 100 without changing phase into a gaseous form. Following filling of cylindrical portion 88 of vessel 60, doors 86 are closed and vessel 60 is lifted to the surface of body of water 26 for unloading to a ship or land based facility with appropriate temperature controls.

While in the foregoing, embodiments of the present invention have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, it may be apparent to those of skill in the art that numerous changes may be made in such detail without departing from the spirit and principles of the invention. 

1. A gas hydrate material recovery apparatus useable below the surface of a body of water in combination with a source of natural gas, comprising: a. a vessel, said vessel including walls forming an inner chamber, said vessel including an inlet and an outlet, said inlet receiving natural gas for said source and said outlet conducting natural gas from said vessel; b. a cooler for removing heat from said chamber of said vessel to form solid gas hydrate material; c. an anchor for removably holding said vessel below the surface of the body of water; and d. a passageway for permitting the entrance and egress of water relative to said vessel chamber.
 2. The apparatus of claim 1 in which said cooler comprises a plurality of conduits passing through said chamber of said vessel, said plurality of conduits carrying cooling fluid therethrough.
 3. The apparatus of claim 1 which additionally comprises a vibrator imparting a force on said walls of said vessel.
 4. The apparatus of claim 1 which further comprises a level indicator determining the position of gas hydrate material within the chamber of said vessel.
 5. The apparatus of claim 1 in which said vessel is a flexible body.
 6. The apparatus of claim 1 which additionally comprises a recirculation conduit for transporting natural gas between portions of said vessel chamber.
 7. A gas hydrate material recovery apparatus useable below the surface of a body of water in combination with a flow of solid gas hydrate particles from below the solid floor of the body of water; comprising: a. a vessel, said vessel including walls forming an inner chamber, said vessel including and inlet and an outlet, said inlet further comprising a mouth receiving the solid gas hydrate particles; b. a door for controlling access to said vessel and said vessel inlet; c. an anchor for removably holding said vessel below the surface of the body of water; and d. a passageway for permitting the entrance and egress of water relative to said vessel chamber.
 8. The apparatus of claim 1 which additionally comprises a vibrator imparting a force on said walls of said vessel.
 9. The apparatus of claim 1 which further comprises a level indicator determining the position of gas hydrate material within the chamber of said vessel.
 10. The apparatus of claim 1 in which said vessel is a flexible body.
 11. The apparatus of claim 7 which additionally comprises an agitator for freeing solid gas hydrate particles from below the solid floor of the body of water;
 12. the apparatus of claim 11 which further comprises a support structure for holding said agitator to said vessel. 